Invalid IK results while switching from OpenSim 3.3 to OpenSim 4.0

Provide easy-to-use, extensible software for modeling, simulating, controlling, and analyzing the neuromusculoskeletal system.
POST REPLY
User avatar
Marcos Alfredo Núñez
Posts: 22
Joined: Thu Sep 01, 2016 1:41 pm

Invalid IK results while switching from OpenSim 3.3 to OpenSim 4.0

Post by Marcos Alfredo Núñez » Wed Aug 08, 2018 5:14 am

I found a really strange behaviour with IK in the new OpenSim 4.0 beta. It looks as if the new IKTool ignores the clamps in angles, giving invalid results.

I attach as an example a clamped model, a .trc experimental markers file and their corresponding IKSetup.xml for the IKTool, for fast comparison. I also attached an unclamped version of the model for reference.

In this example, the right hip clamp seems to be ignored in OpenSim 4.0.
Attachments
IKtest.zip
(114.09 KiB) Downloaded 19 times

Tags:

User avatar
jimmy d
Posts: 1375
Joined: Thu Oct 04, 2007 11:51 pm

Re: Invalid IK results while switching from OpenSim 3.3 to OpenSim 4.0

Post by jimmy d » Fri Aug 10, 2018 2:00 pm

Thanks for reporting, we will have a look and get back to you shortly. 4.0 is still in Beta so we expect some bugs.

User avatar
jimmy d
Posts: 1375
Joined: Thu Oct 04, 2007 11:51 pm

Re: Invalid IK results while switching from OpenSim 3.3 to OpenSim 4.0

Post by jimmy d » Fri Aug 10, 2018 2:51 pm

Hi, Marcos-

I am not seeing the issue that you identified. I changed the clamped version of your Model, adjusting the hip_roation_r coordinate to a have a more restrictive range (-3 to 3 degees). When I run IK in 3.3 and 4.0, I see the coordinates values constrained between these values. When I unclamp the right hip, the results exceed the -3 to 3 range, which I would say is the correct behavior.

Could you perhaps describe what you would expect when a coordinate is clamped during IK which will help me verify out what you are seeing?

POST REPLY